Fiee alaem telegraph



v 0. H RUDD. FIRE ALARM TELEGRAPH.

Nb. 511,462. Patented Dec. 26,1893.

U ITED STATES PATENT OFFICE CHARLES H. RUDD, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE WESTER ELECTRIC COMPANY, OF SAME PLACE.

Fl RE-ALARM TELEG RAPH.

SPECIFICATION forming part of Letters Patent No. 511,462, dated December 26, 1893. Application filed May 19, 1892. Renewed May 15, 1893. Serial No. 474.287- (No model.)

To all whom it may concern:

Be it known that I, CHARLES H. RUDD, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Fire-Alarm Telegraphs, (Case No. 18,) of which the following is a full, clear, concise, and exactdescription, reference being had to the accompanying drawings, forming a :0 part of this specification;

My invention relates to that class of automatic electric fire alarms which is operated with closed circuit.

Its object is to provide a method of indieating at a central station the occurrence of a ground at a substation or district, as I prefer to call a building protected by the system, of which the present invention constitutes an improvement, and which is more generally described in my application Serial No. 408,581.

In this system it is a matter of great importance that the meallic circuit, which starts out from a central station and passes through each district and then returns to the central station, and also branches of this metallic circuit, should be kept free from ground connections, and to that end it is the aim of my invention to provide means whereby the ground occurring in any district will be indicated at the ceno tral station, and further will cause the dis- 40 not therefore aim in myinvention to provide means for automatically locating grounds 1 upon the metallic circuit between districts.

It will be understood that a district may include several floors of a building, or it may be divided into subdistricts in various ways. In considering my invention, however, it is only necessary to deal with one undivided district and the central station, which are accordingly represented in the accompanying 5o drawings which illustrate my invention.

Figure 1 is a diagrammatic illustration of the system to which myinvention is applied. Fig. 2 is a diagrammatic illustration showing the modificationof the system which is introduced by my invention. Fig. 3 shows a further modification by substituting for the resistance of Fig. 2 a differential magnet. Fig. 4 represents another step in the complete invention under consideration, in which a supplementary battery is introduced between the central station ground and the metallic circuit. Fig. 5 shows the complete invention embodying the various steps, and also the addition of a detector or galvanometer introduced between the supplementary battery and the metallic circuit.

. In referring to the diflierent figures, I use similar letters of reference to indicate similar parts. 7

The differential magnet to has two coils adapted to act in opposition to each other upon the armature b. When both coils are energized with currents of the same polarity, one of said coils a is included in the main circuit, and I also include in this same circuit a resistance 1", shown in Fig. 2. The

other coil a of the neutral relayis included in ashunt or branch circuit, which branch circuit includes suitable heat responsive devices o c c, and in the modification of my invention the resistance r shown in Fig. 2. The branch and the main circuits are divided at d and reunite at e. The attraction of the armature 12 operates in any suitable manner to release mechanism by which the break wheel fis rotated; this break wheel operating to open and close the circuit and thus send to the central office the number of the district. As mechanism .for accomplishing this iswell known, I represent only the essential parts thereof by the catch g adapted to be raised by the lever h attached to the armature and pivoted at 2'; thus releasing the break Wheel f which is rotated by the spring or Weight 70. Upon the periphery of the break wheel f are teeth arranged to press against the lever Z, thus opening the contact at by means of which a signal is transmitted to the central office through the operation of aback contact relay and register located there and indicated by the letter a. The main battery 0, which operates the entire system, is located preferably at thecentralptiice. The ground 1), the supplementary battery q and the detector 3 have functions to perform in accomplishing the results to be obtained, which will be understood by the description of the operation of the above described apparatus and circuits.

The method of operation of the apparatus and circuits shown in Fig. 1 is set forth in my application Serial No. 408,581. I will briefly refer to this method of operation. WVhen the circuit is broken by the fusing of any one of the thermostats in the district, or by the actuation of the heat responsive devices in any suitable way to open the branch circuit which includes the coil a? of the differential magnet, the ditterential magnet on, which has hitherto been unmagnetized owing to the opposing currents of the same polarity and equal strengthiiowing through the two coils, becomes ,Inagnetized by the current flowing through the main circuit and the coils a," included therein. The armature b is thereby thus releasing th break wheel an" transmitting to the recording apparatus of central office the number of the district. p r the purpose of notifying the central of any disturbance of the system, such as occurs by a ground connection having been put on at a district, without in any wise interfering with its operation of sending an when the circuit is open by one of the heat responsive devices, I add the resistance included in the main circuit and 7' included in branch circuit and the ground 19 at the central station. The resistance 0" I make egua l to the resistance of the branch circuit ineluding the resistance rand the heat responsive devices 0 c c. This resistance 1' may be made adjustable, but ordinarily this is not necessary as a close enough balance can be secured with an ordinary resistance coil. As resistances r and r" are in practice in proximity toeach other, any groundthat is liable to ocour in a district willdevelop between the res st ancen" and the diiferential magnet a. The result era ground connection would be to cut out the resistance r from the shunt circuit and thus balance the system, allowing suflicient current to how through the coil (t to attract the armature b and send in the number of the district to the central office in the orama mamer. For the pu pose cf adding to the certaint and force with which this apparatus operates, I windtheresistances r, 4" upon a core, makinga second dilferential magnet t. The functions of 1' and 7", as resistances, remain as before, but an additional function is given by thus disposing of them upon a core, namely, the preservation of an unmagnetiaed ccndit ic'n of the coil of the diflferential magnet t, whilethe system is balanced, as it is under normalccnditicns, and the magnetization of the, core of this difiere'ntial magnet when the system is unbalanced, in a manner to coo the te'tnperature above cei crate with the differential magnet (b As when rand r are simple resistances, a ground upon the branch circuit will cut out the coil 1, leaving the coil 4' in circuit and co-operating with coil a to move the armature 1) upon its pivot 45, thus releasin the mechanism of the break wheel, and sending the' signal in the usual way. To make this apparatus and arrangement of circuits still more ef fective, I add the supplementary battery q between the main circuit and the ground 19 at the central office, and dispose this battery so that it will co-operate with the main battery o in its action upon coil a that is,I preferably arrange the supplementary battery so that it will be in series with the mainbattery 0 in its operation, upon magnet a' when the ground occurs within the limits of the district. n M c For the purpose of distinguishing between a signal indicating a ground aai tnccajru a signal indicating that the heat responsive device is. operated td dpen the circuit in the way in which it is designed, up t c t in predeten mined point, I connect into the circuit between the main circuit andthegrcundat the central oflice, the detector s' which will respond to the current which finds ground, but will not respond to the opening of the circuit in acase where it Is intended that an alarm should be recorded.

Having thus described my invention, what I claim as new, and desire tosecure by Let ters Patent, is 1 fl 1. In an auto'tnatic electric fire alarm, the combination with a netallic circuit amend n from the central ofiice thr'oug'h the districtor districts to be prctected, of a diherential net having two sons adapted to act in appssition to each other upon an armature when both are nergized with currents of thesaule polarity,

one of said cells be ingincmded in the branch circuit together with neat resectsive devices adapted to open the circuit when actuated, and a resistance coil, the jiiain circuit including the other of said coils, and a resistance about equal to the resistance in the branch circuit including the heat respcnsive devices, said main circuit shunting the said first coil, the heat responsive devices and the branch circuit resistance, mechanism adapten to be actuated by said difierential mag nets, whereby a signal is sent t6 the central Mice, and the ground connection rattle cemtt'al oflice, substantially as described.

2.111 a-closed circuit signaling systenthe combination with a main circuit extendin from the central oflice through the districts to be protected, 'of two differential magnets adapted to ri -operate ripen thesaine armature lever, each of said differential magnets having one 'of its coils included said tna'incircuit, and the other cf its coils included in a branch circuit, which branch circuit alsci'ncludes heat responsive devices, mechanism n are use of its wayw adapted to be actuated by said differential sition to each other upon an armature when both are energized with currents of the same polarity, one of said coils being included in the branch circuit together with heat responsive devices adapted to open the circuit when actuated, and a resistance coil, the main circuit including the other of said coils, and a resistance about equal to the resistance in the branch circuit including the heat responsive devices, said main circuit shunting the said first coil, the heat responsive devices and the branch circuit resistance, mechanism adapted to be actuated by said differential magnets, whereby a signal is sent to the central office, the ground connection at the central station, and a supplementary battery connected between the ground and the main circuitadapted to co-operate with the battery in said main circuit.

4. In an automatic electric fire alarm, the combination with a metallic circuit extending from the central office through the district or districts to be protected, of a differential mag net having two coils adapted to aotin'opposition to each other upon an armature when both are energized with currents of the same polarity, one of said coils being included in the branch circuit together with heat responsive devices adapted to open the circuit when branch circuit including the heat responsive devices, said main circuit shunting the said first coil, the heat responsive devices and the branch circuit resistance, mechanism adapted to be'actuated by said difierential magnets, whereby a signal is sent to the central office, the ground connection at the central station, and a galvanometer located between said ground connection and the main c rcuit.

5. The combination with an electric alarm circuit extending from a central station through a district to be protected, of two electro magnetic helices in different parallel branches of said circuit, heat responsive devices adapted to open the circuit when actuated included in one of said branches, a resistance coil in the branch with the heat responsive devices, and mechanism adapted to be actuated by the energization of one only of said helices, but to be prevented from operation by the simultaneous energization of both helices to send a fire alarm signal, substautially as described.

6. The combination with a fire alarm cir cuit, of two electro-magnetic helices in different parallel branches thereof adapted to act in opposition to each other upon an armature, heat responsive devices adapted to open the circuit when actuated, and a resistance coll included in one of said branches,mechanism controlled by said armature for sending the fire alarm signal, and a ground branch from the main circuit, substantially as described.-

In witness whereof I hereunto subscribe my name this 3d day of February, A. D. 1892.

M. J EANE TALLETT, GEORGE L. CRAGG. 

